Question

（a的2次方减4a加4分之a-1减去a的2次方减2a分之a加2）除以（a分之4减1）

Answer 1

原式=[(a-1)/(a²-4a+4)-(a+2)/(a²-2a)]÷[(4/a)-1]
={ (a-1)/(a-2)²-(a+2)/[a(a-2)] }÷[(4-a)/a]
={ a(a-1)/[a(a-2)²]-(a+2)(a-2)/[a(a-2)²] }×[a/(4-a)]
={ [a(a-1)-(a+2)(a-2)]/[a(a-2)²] }×[a/(4-a)]
={ (a²-a-a²+4)/[a(a-2)²] }×[a/(4-a)]
={ (4-a)/[a(a-2)²] }×[a/(4-a)]
=1/(a-2)²